title: TTF-1 expression in breast carcinoma: an unusual but real phenomenon.
abstract: OBJECTIVE
  To evaluate thyroid transcription factor-1 (TTF-1) expression in a large cohort of invasive breast carcinomas (IBCs) using two commercially available monoclonal antibody clones (8G7G3/1 and SPT24).
  
  
  RESULTS
  Nuclear and cytoplasmic TTF-1 expression was evaluated in 1132 primary IBCs and 208 primary pulmonary carcinomas using tissue microarray (TMA) sections. TTF-1 nuclear expression was detected in one of 1132 (0.09%) IBCs by 8G7G3/1. In pulmonary carcinoma, TTF-1 expression was detected in 149 (71.6%) and 147 (70.6%) cases by 8G7G3/1 and SPT24, respectively, with no significant difference being seen between the two clones (P = 0.839), and there was good consistency between these two antibodies in differentiating breast and pulmonary carcinomas (kappa value 0.905; P < 0.001). Both clones showed high specificity but relatively low sensitivity. Cytoplasmic TTF-1 expression was detected in 44 IBCs by 8G7G3/1, and this particular expression pattern was an independent adverse prognostic factor.
  
  
  CONCLUSIONS
  Both TTF-1 antibodies (clones 8G7G3/1 and SPT24) were useful in differentiating breast from pulmonary carcinomas. Nuclear expression of TTF-1 was detected in IBCs by 8G7G3/1, but not by SPT24. Cytoplasmic expression of 8G7G3/1 was seen in IBC for the first time, and was an independent unfavourable prognostic factor.
authors.affiliation: Department of Anatomical and Cellular Pathology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Yun-Bi
authors.initials: YB
authors.lastname: Ni
authors.forename: Julia Y S
authors.initials: JY
authors.lastname: Tsang
authors.forename: Mu-Min
authors.initials: MM
authors.lastname: Shao
authors.forename: Siu-Ki
authors.initials: SK
authors.lastname: Chan
authors.forename: Joanna
authors.initials: J
authors.lastname: Tong
authors.forename: Ka-Fai
authors.initials: KF
authors.lastname: To
authors.forename: Gary M
authors.initials: GM
authors.lastname: Tse
mesh_terms: D000911:Antibodies, Monoclonal; D014408:Biomarkers, Tumor / Q000276:immunology / Q000378:metabolism; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D002467:Cell Nucleus / Q000378:metabolism; D015331:Cohort Studies; D003593:Cytoplasm / Q000378:metabolism; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009687:Nuclear Proteins / Q000276:immunology / Q000378:metabolism*; D011379:Prognosis; D000074482:Thyroid Nuclear Factor 1; D046888:Tissue Array Analysis; D014157:Transcription Factors / Q000276:immunology / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; D014408:Biomarkers, Tumor; C000614412:NKX2-1 protein, human; D009687:Nuclear Proteins; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors
keywords: TTF-1; breast carcinoma; pulmonary carcinoma